Different TGM1 mutation spectra in Italian and Portuguese patients with autosomal recessive congenital ichthyosis: evidence of founder effects in Portugal.

Autosomal recessive congenital ichthyosis (ARCI) is a clinically and genetically heterogeneous group of cornification disorders characterized by generalized scaling of the skin. Mutations in the TGM1 gene occur in many patients with lamellar ichthyosis and also in patients with less severe forms of ARCI. We analyze the TGM1 gene locus in Italian and Portuguese patients with different clinical presentations of ARCI. We found that allelic heterogeneity at TGM1 is higher in Italy than in Portugal. Moreover, we evidenced founder effects for Portuguese TGM1 disease-associated alleles.